instructions
a --
POP -> Pops a byte off the stack
POPw -> Pops a word off the stack
POPx -> Pops a byte off the stack to x
POPxw -> Pops a word off the stack to xw
POPy -> Pops a byte off the stack to y
POPyw -> Pops a word off the stack to yw
POPxy -> Pops a byte off the stack to x and y
POPxyw -> Pops a word off the stack to xw and yw